Steam generator

ABSTRACT

An injection head introduces H 2  and O 2  into one end of an elongate combustion chamber. At the same time, water is injected into the chamber through peripheral ducts to form a water curtain, or through inlets in the injection head, or through apertures facing away from the injection head in water-cooled tubing extending in a plane perpendicular to the chamber axis.

This application is a division of application Ser. No. 209,687, filedNov. 24, 1980 U.S. Pat. No. 4,377,067.

The invention relates to a steam generator in which gaseous hydrogen andgaseous oxygen can be introduced by means of an injection head into acombustion chamber and can be burnt therein, the generator having inletaperture for the injection of liquid (referred to below simply as water)into the combustion chamber.

BACKGROUND OF THE INVENTION

A steam generator is described in German patent specification No. 1 301821 in which fuels which cannot usually be completely condensed areburnt in a combustion chamber and the combustion gases flow through thecombustion chamber to an outlet. Water is injected into the combustiongases through apertures which are disposed alongside the flow path inthe side wall of the combustion chamber at the location of a ductconstriction and such water evaporates owing to the elevated temperatureof the combustion gases. The superheated steam generated by means ofthis device is used particularly for the operation of ejectors in orderto operate altitude simulation systems.

Such a rocket propulsion drive combustion chamber would also be suitablefor generating steam which can be used for driving a turbine. In thiscontext, it is essential for the gas generated by the combustion chamberto be completely condensable, i.e. no combustion gas residue mustremain.

This requirement can be satisfied with particular advantage if hydrogenand oxygen are used as combustion gases in a stoichiometric ratio sincewater is produced by complete combustion. The addition of water to thehot combustion gases also reduces the temperature of the combustiongases, thus achieving a temperature of the order of 900° C., which isacceptable for the operation of turbines.

The efficiency of such combustion chambers is naturally particularlyhigh when the most uniform possible contact between the injected waterand the hot combustion gases is achieved, because the evaporation ratewill then be an optimum. What is desired is a steam generator whichpermits particularly advantageous utilisation of the thermal energywhich is stored in the hot combustion gases.

SUMMARY OF THE INVENTION

In accordance with the invention the apertures for injecting water intothe combustion chamber are arranged so that water can be injected intothe combustion gas stream over the entire cross-section of thecombustion chamber.

One preferred embodiment of the invention provides that inlet ducts forwater are disposed in two inlet planes, positioned perpendicularly withrespect to the gas flow direction, and are situated at a distance fromeach other in the gas flow direction in a wall which surrounds thecombustion chamber, and said ducts are orientated so that the jets whichemerge from two ducts disposed in different inlet planes, strike eachother along a rebound plane which is disposed between the two inletplanes, so that a water curtain extending substantially perpendicularlywith respect to the gas flow direction is produced by the totality ofwater jets which impinge upon each other.

A water curtain of this kind can advantageously enter into the flowinggases over the entire cross-section of the combustion chamber.

In this context it is advantageous if the distance between adjacentinlet planes is short in relation to the length of the combustionchamber.

Advantageously, a plurality of pairs of inlet planes is provided alongthe combustion chamber. The distance between different inlet plane pairscan increase with the distance from the injection head.

Another preferred embodiment provides that inlets for water are disposedin the injection head in addition to inlet ports for hydrogen andoxygen. In this embodiment it is therefore possible for water to beinjected from an end face injection plate of the injection head into thecombustion chamber over the entire cross-section thereof so that theliquid water is mixed particularly advantageously with the combustiongases. To this end, it is advantageous if the water inlets aredistributed substantially over the entire cross-sectional area of thecombustion chamber.

Another preferred embodiment of the invention provides that, in a planewhich extends perpendicularly with respect to the longitudinal axis ofthe combustion chamber, there is provided at least one tube, theinterior of which is divided by means of a bulkhead into a firstcompartment nearer to the injection head and into a second compartmentwhich is distal from the injection head, the first compartment isprovided with a cooling water supply and cooling water discharge meansso that cooling water can be conducted therethrough, and the secondcompartment is provided with a water supply and with apertures, situatedon the side which is distal from the injection head, so that water canbe injected through this compartment into the combustion chamber.

This construction also permits water to be introduced into thecombustion gases over the entire diameter of the combustion chamber,more particularly if high pressures prevail in the combustion chamber.The tubing extending into the combustion chamber is adequately cooledbecause cooling water is conducted on the side nearer to the injectionhead.

The tubing may consist of a single tube. It is advantageous if thesecond compartment communicates via a closable duct with the coolingwater discharge means of the first compartment. The water, used forcooling the tubing and therefore preheated, can thus be used asinjection water.

In a further development, it is possible to arrange for several tubes tobe combined into a tube system, while leaving space to allow the passageof combustion gases beween the individual tubes. For example, the tubesystem can comprise two intersecting tubes or three tubes which convergein the combustion chamber middle and are offset with respect to eachother by 120°. It is also possible for the tube system to comprise aplurality of parallel tubes intersecting with a plurality of tubesextending perpendicularly thereto.

It is advantageous in all embodiments if the injection head comprises aninjection plate which consists of sintered metal and is permeable togaseous hydrogen and through which oxygen injection ducts (and, whereappropriate, water injection ducts) extend; preferably the injectionplate closes a cavity which is situated in the body of the injectionhead, extends to the combustion chamber, and communicates with ahydrogen duct. This permits introduction of the hydrogen into thecombustion chamber in very uniform distribution over the combustionchamber cross-section and advantageous mixing of the combustion gases isobtained thereby. The gas cushion in front of the injection plate alsoprovides thermal insulation, i.e. the injection plate is shielded fromthe hot combustion gases.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the accompanying drawings, in which:

FIG. 1 is a diagrammatic longitudinal sectional view of a steamgenerator;

FIG. 2 is an enlarged part view of the region designated A in FIG. 1;

FIG. 3 is an enlarged partial sectional view of an embodiment of aninjection head for a steam generator;

FIG. 4 is a partial sectional view of another embodiment of an injectionhead for a steam generator;

FIG. 5 is an enlarged view of the region designated B in FIG. 4;

FIG. 6 is a diagrammatic sectional view of another embodiment of a steamgenerator, with a water injection tube which extends across thecombustion chamber.

FIG. 7 is a section along the line 7--7 of FIG. 6;

FIG. 8 is a section of an injection tube system in a preferredembodiment, the section being taken in the same plane as in FIG. 7;

FIG. 9 is a view similar to FIG. 8 of another preferred embodiment of aninjection tube system; and

FIG. 10 is a view similar to FIG. 8 of another preferred embodiment ofan injection tube system.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a steam generator which comprises a combustion chamber 1surrounded by a shell or housing 2. Advantageously, the cross-section ofthe combustion chamber 1 is circular. At one end the combustion chamberis closed by an injection head 3 which contains a distributor chamber 5for hydrogen, communicating with a duct 4, and a distributor chamber 7for oxygen, communicating with a duct 6. Both distributor chambers 5 and7 communicate with corresponding inlet ports in the injection head 3, sothat hydrogen and oxygen can pass from the distributor chambers into thecombustion chamber.

The shell 2 in the illustrated embodiment is of segmental construction,i.e. segments 8,9,10,11,12,13,14 adjoin each other. This facilitates anychange of the construction of the steam generator for experimentalpurposes but is not absolutely necessary for the operation of thecombustion chamber, i.e. the shell can be constructed, for example,integrally. A pilot ignition chamber 15, communicating with thecombustion chamber 1, is disposed in the segment 8 adjacent to theinjection head 3. A hydrogen supply duct 16 and an oxygen supply duct 17extend into the ignition chamber 15. An ignition electrode 18 extendsinto the ignition chamber 15.

The various segments 8, 10, 12, and 14 are provided with ducts 19 intowhich cooling water can be introduced via supply ducts 20, which coolingwater is at least partially returned through cooling water dischargeducts to a cooling device in a manner not shown. The ducts 19 extendparallel with the longitudinal axis of the combustion chamber close tothe circumferential surface defining the combustion chamber and eachcommunicates by means of a radial portion 21 with annular chambers 22.Annular chambers 22 of adjacent segments 8 and 9, 10 and 11, or 12 and13 communicate with each other by means of a connecting duct 23. Aradial duct 24 extends from the outer annular chamber 22 in each of thesegments, 9, 11, 13 to an inner annular chamber 25 which communicatesalong is circumference by means of a plurality of inlet ducts 26, 27with the combustion chamber 1. The region of the annular chamber 25 andof the inlet ducts 26, 27 is shown in enlarged form in FIG. 2. It can beseen that a first group of inlet ducts extends into the combustionchamber along the periphery of a first plane perpendicular to the gasflow direction, while a second group of inlet ducts extends into thecombustion chamber along the periphery of second plane parallel with thefirst plane but offset in the gas flow direction. The entry regions ofthe inlet ducts 26 of the first group and of the inlet ducts 27 of thesecond group are orientated towards each other, so that the water jetsemerging therefrom meet in a plane between the exit planes of the inletducts 26, 27. The compact water jets are torn apart into small dropletsin this impact plane and are diverted into a substantially radialdirection. The inlet ducts, which are distributed along thecircumference of the combustion chamber, therefore cause an inwardlyoriented water curtain to be produced in the impact plane, by means ofwhich curtain the hot combustion gases can be loaded with liquid waterover the entire cross-section of the combustion chamber.

A water inlet element of this kind is provided in each segment 9, 11,13. The distances between the inlet elements can increase along thecombustion chamber axis, since the temperature of the combustion gasesdrops as a result of successive loading with liquid water and sinceaccordingly the process of evaporation is slowed down from one to thenext water inlet element.

In view shown in FIG. 1, the combustion chamber is shown broken off atits exit side. At that place, the combustion chamber can extend into aturbine casing.

In operation of the combustion chamber illustrated in FIG. 1 uniformloading of the combustion gases with water and therefore an optimumevaporation efficiency can be achieved by the water injection describedabove.

Furthermore, the pilot ignition chamber 15 permits gentle commencementof operation of the combustion chamber. The combustion process can bestarted in the ignition chamber 15 by means of the hydrogen and oxygengases supplied thereto, while the supply of hydrogen and oxygen to themain combustion chamber 1 is restricted. The hot combustion gasespassing from the ignition chamber 15 into the combustion chamber 1ignite the gases therein, but this does not result in any suddenpressure rise which could damage the turbine or other equipmentconnected downstream. As soon as combustion commences in the combustionchamber 1, the gas supply therein can be increased to the normal rate,so that combustion takes place at the full extent.

The ignition chamber 15 of the exemplified embodiment shown in FIG. 1 isinclined in the flow direction i.e. its longitudinal axis forms an acuteangle with the flow direction.

FIG. 3 shows part of a modified embodiment of an injection head. Acombustion chamber 31 is surrounded by a shell or housing 32 whichcontains cooling water ducts 33 as in the embodiment illustrated inFIG. 1. An injection plate 34 closes the end face of the combustionchamber 31. Inserts 35, 36, 37 and 38, of substantially cup-shapedconfiguration, adjoin the injection plate 34 and are placedconcentrically one upon the other so as to be sealed against each other.A first cavity 39 is defined between the insert 35 and the injectionplate 34, a second cavity 40 is defined between the insert 35 and theinsert 36, a third cavity 41 is defined between the insert 36 and theinsert 37, and a fourth cavity 42 is disposed between the insert 37 andthe insert 38. The first cavity 39, adjacent to the combustion chamber,communicates with a supply duct 43 and delivery ports 44 so that coolingwater can be conducted through the cavity 39. Ports 45 in the injectionplate 34 extend from the cavity 39 into the combustion chamber 31.Cooling water which flows through the cavity 39 can thus pass at leastpartially through the ports 45 into the combustion chamber.Advantageously, the ports 45 are uniformly distributed over the surfacearea of the injection plate 34 so that uniform injection of water ismade possible over the entire cross-section of the combustion chamber.

The second cavity 40, disposed next to the cavity 39, is provided todischarge the cooling water, which enters the cavity 40 throughdischarge ports 44 and emerges therefrom through a discharge duct 46.

The third cavity 41, communicates with a hydrogen supply duct 48 and thefourth cavity 42 communicates with an oxygen supply duct 49. A pluralityof tube members 52 are provided to supply the fuels to the combustionchamber. The tube members are inserted through bores in the insert 37,through bores in the insert 36, through bores in the insert 35, andthrough bores in the injection plate 34, to extend into the combustionchamber 31 and are welded to the walls of the cavities. The cavities 39,40, 41 and 42 remain separated from each other by means of the weldingseams; the bores 53 of the tube members 52 connects the cavity 42 to thecombustion chamber, ducts 55 around the tube members connect the cavity41 to the combustion chamber, and the ports 45 connect the cavity 39 tothe combustion chamber.

A bush 56 passes along the axis of symmetry of the arrangement throughconcentric bores in the inserts 35, 36, 37, and 38 and in the injectionplate 34 in a sealing manner. A pilot ignition chamber 57 is insertedinto the bush 56 and retained therein by means of spacer weld spots 58so that an annular gap 59 is produced between the bush 56 and the wallof the ignition chamber 57. This annular gap 59 communicates with ahydrogen supply duct 60 through which hydrogen gas can be conducted forcooling purposes through the annular gap.

A hydrogen supply duct 61 and an oxygen supply duct 62 extend into theignition chamber 57. An electric ignition electrode 63 is disposed atthe end of these ducts, remote from the combustion chamber 31.

Apart from the means for supplying water through the injection plate asalready described, the injection head illustrated in FIG. 3 differs fromthe injection head of FIG. 1 in particular by virtue of the ignitionchamber being integrated with the injection head. In principle, themethod of operation is the same as described above.

This device ensures uniform and thorough mixing of the combustion gaseswith water and therefore ensures optimum evaporation performance, moreparticularly in the region of the injection head. The concentric supplyof hydrogen and oxygen through the central bores 53 and through theducts 55 ensures thorough mixing of the combustion gases and this inturn ensures complete combustion of the gases, as is essential forperforming a circulating process.

FIG. 4 shows another exemplified embodiment of the injection head of thesteam generator in diagrammatic form. In this embodiment, a combustionchamber 71 is surrounded by a jacket 72 in which cooling water ducts 73are disposed. A pilot ignition chamber 83 is provided as described abovewith reference to the ignition chamber 15 in FIG. 1.

The injection head 74 has two cavities 75 and 76 which are connected toan oxygen duct 77 and a hydrogen duct 78 respectively. The cavity 76,closest to the combustion chamber 71, is separated from the combustionchamber by means of an injection plate 79 of sintered metal. This can beproduced for example, by the application of heat and pressure to smallalloy-steel balls, and is so porous that the gaseous hydrogen can enterthe combustion chamber 71 from the cavity 76. A bulkhead 80, whichseparates the cavities 75 and 76 from each other, has extensions 81,each with a central bore 82, which reach through the cavity 76 andthrough the injection plate 79 into the combustion chamber 1. Oxygen canenter through these extensions or ducts 81 into the combustion chamber71. It can be seen that the oxygen, conducted through the extensions 81into the combustion chamber 71 can mix intimately in the entry regionwith the hydrogen which passes through the porous injection plate 79, sothat a particularly homogeneous gas mixture is obtained in thecombustion chamber.

A modified system for injecting water into the combustion gases isillustrated in FIGS. 6 and 7. FIG. 6 shows in diagrammatic form acombustion chamber 91 with a shell 92 and an injection head 93 which issupplied with the hydrogen and oxygen gases through ducts 94 and 95,respectively. One region 96 of the shell 92 serves as a cooling andwater-injection element and accomodates an annular duct 97 into whichcooling water can be introduced via ducts 98 and 99 (FIG. 7). Theannular duct 97 communicates with a tube 100 which extends diametricallyacross the combustion chamber 91. The tube 100 is divided by a bulkheador partition 101 into two components 102 and 103. The first compartment102 (proximal to the injection head 93) communicates at one end with theannular duct 97 and is provided at the opposite end with an exit duct104. The second compartment 103 (distal from the injection head 93) isclosed at one end with respect to the annular duct 97 by means of an endplate 105 and at its opposite end it communicates with an inlet duct106. The exit duct 104 is connected to the inlet duct 106 via achangeover valve 107 through which the exit duct 104 can be optionallyconnected to the inlet duct 106 or to a discharge duct (not shown). Onthe side which is distal from the injection head 93 the tube wall isprovided with a plurality of apertures 108 through which the compartment103 communicates with the combustion chamber 91.

In operation, the cooling water which enters through the ducts 98 and 99into the annular duct 97 first serves to cool the combustion chambershell 92 and, owing to the relatively small cross-section of thecompartment 102, then flows at high velocity through the compartment102. This ensures highly effective cooling of the tube 100 which isexposed to the hot combustion gases. All of the cooling water emergingfrom the exit duct 104 can be conducted to the discharge duct (notshown) but it is possible for part of such water to enter via the inletduct 106 into the compartment 103 from where it is injected throughapertures 108 into the combustion chamber 91 away from the injectionhead 93. Injection of water is performed over the entire diameter of thecombustion chamber, so that combustion gases close to the axis of thecombustion chamber can also be laden with water.

The injection system just described has a single tube 100 which extendsdiametrically across the combustion chamber. It is of course possiblefor a more complicated tube system to be employed instead of the singletube 100. Examples of modified tube systems are shown in diagrammaticform in FIGS. 8 to 10. In the example shown in FIG. 8, the tube systemcomprises two intersecting tubes 110 and 111 which extend diametricallyacross the combustion chamber at 90° to each other. In the example ofFIG. 9 the tube system comprises three tubes 120, 121, 122 which join inthe centre of the combustion chamber and are offset through 120°relative to each other. Finally, in the exemplified embodimentillustrated in FIG. 10, the tube system comprises a plurality ofintersecting tubes 130 between which interstices 131 remain throughwhich the combustion gases can flow. The important feature in all thesesystems is that cooling water flows at high velocity through the tubesystem side nearest to the injection head so that highly effectivecooling is achieved. Injection of water is performed on the oppositeside, i.e. on the downstream side.

We claim:
 1. A steam generator, comprising(a) means defining acombustion chamber having a peripheral wall; (b) an injection head forintroducing gaseous hydrogen and gaseous oxygen into said combustionchamber, whereby a flow of hot gas along said combustion chamber isproduced; (c) and first and second groups of water inlet ducts containedin said combustion chamber peripheral wall, said first and second groupsof ducts opening into the combustion chamber along the respectiveperipheries of first and second inlet planes which are substantiallyperpendicular to the gas flow direction, the ducts of said first andsecond group being oriented so as to produce water jets which meet in animpact plane between the two inlet planes so that a water curtainsubstantially perpendicular to the gas flow direction is produced by thetotality of water jets which impinge upon one another.
 2. The steamgenerator of claim 1, in which the distance between the inlet planes issmall in relation to the length of the combustion chamber.
 3. The steamgenerator of claim 1, in which there are a plurality of pairs of saidduct groups along the combustion chamber.
 4. The steam generator ofclaim 3, in which the distance between the duct group pairs increaseswith the distance from the injection head.
 5. The steam generator ofclaim 1, in which all the inlet ducts of each group communicate with acommon annular water-supply duct in the peripheral wall of thecombustion chamber.
 6. The steam generator of claim 1, in which theinjection head comprises a plate which consists of sintered metal and ispermeable to gaseous hydrogen, and oxygen injection ducts extendingthrough the plate.
 7. The steam generator of claim 6, in which theinjection head includes a body which defines a hydrogen supply cavityextending to the combustion chamber, the said plate closing the saidcavity.
 8. A steam generator comprising a combustion chamber and aninjection head for introducing gaseous hydrogen and gaseous oxygen intothe chamber, the injection head having inlets for injection water intothe chamber.
 9. The steam generator of claim 8, in which the waterinlets are distributed substantially over the entire cross-sectionalarea of the combustion chamber.
 10. The steam generator of claim 8, inwhich the water inlets communicate with a cooling flow cavity in theinjection head.
 11. The steam generator of claim 8, in which theinjection head comprises a plate which consists of sintered metal and ispermeable to gaseous hydrogen, and oxygen injecting ducts and waterinjection ducts extending through the plate.
 12. The steam generator ofclaim 11, in which the injection head includes a body which defines ahydrogen supply cavity extending to the combustion chamber, the saidplate closing the said cavity.
 13. A steam generator comprising acombustion chamber having a longitudinal axis; an injection head forintroducing gaseous hydrogen and gaseous oxygen into one end of thecombustion chamber; tubing extending in a plane substantiallyperpendicular to the longitudinal axis of the chamber within thechamber, the tubing being partitioned longitudinally of the tubing intoa first compartment proximal to the injection head and a secondcompartment distal from the injection head; means for supplying water tothe first compartment and means for discharging water from the firstcompartment so that water is conducted through the first compartment inorder to cool the tubing; and means for supplying water to the secondcompartment, the second compartment having apertures for injecting waterinto the combustion chamber away from the injection head.
 14. The steamgenerator of claim 13, in which the means for supplying water to thesecond compartment communicates with the means for discharging waterfrom the first compartment.
 15. The steam generator of claim 13, inwhich the means for supplying water to the first compartment comprises acooling cavity in the combustion chamber wall, the cooling cavitycommunicating with the first compartment.
 16. The steam generator ofclaim 13, in which the tubing comprises a plurality of tubes.
 17. Thesteam generator of claim 16, in which the tubing comprises two tubeswhich intersect.
 18. The steam generator of claim 16, in which thetubing comprises a plurality of tubes which converge in the middle ofthe combustion chamber, the angle between adjacent tubes being the same.19. The steam generator of claim 16, in which the tubing comprises aplurality of parallel tubes which intersect with a plurality of tubesextending perpendicularly thereto.
 20. The steam generator of claim 13,in which the injection head comprises a plate which consists of sinteredmetal and is permeable to gaseous hydrogen, and oxygen injection ductsextending through the plate.
 21. The steam generator of claim 20, inwhich the injection head includes a body which defines a hydrogen supplycavity extending to the combustion chamber, the said plate closing thesaid cavity.